It is known that stimulation of the right heart cavities may be achieved by the implantation of an endocardial lead that is passed through the right peripheral venous network. However, to stimulate the left heart cavities, the situation is more complex. One solution often adopted is to introduce a lead into the right atrium and then pass it into the coronary system via the coronary sinus ostium. However, this implantation technique is not always feasible, especially when the conformation of the coronary sinus is too rough, or there is thrombosis.
Another solution, called the “transeptal approach” is to pass the lead through the interventricular or interatrial septum, or “cardiac septum”, to stimulate the left heart atrial or ventricular cavity, depending on the configuration and placement of the lead. This procedure, as currently implemented, however, presents high operative risks, including, for example, accidental perforation of the aorta or dissection of the right atrium wall by a sudden, unintentional rotational movement of the needle. In any case, this technique is very difficult to implement and requires great skill by the surgeon who must be able to cross the septum and ensure a perfect positioning of the lead on the wall. Crossing of the septum is typically not to undertaken if there remains any doubt about the position of the needle.
The EP 1 516 644 A1 and its counterpart U.S. Pat. No. 7,620,457 describe a kit for penetrating the cardiac septum and for the placement of a trans-septal device that avoids the foregoing problems. The proposed technique is to implement a penetrating guide comprising a lead that is equipped at its distal end with a helical screw and a catheter guide having an internal lumen. The screw is oriented to be screwed into the wall of the septum in the location of the selected perforation site. Once the screw is anchored in place, the physician introduces a penetrating stylet into the internal lumen. The stylet is progressively driven into the guide catheter to puncture the septum, while being guided by the lead head anchored in place by the helical screw. This is said to secure the progression of the penetrating stylet. Once the septal wall is crossed, the guide catheter is pushed by the physician to penetrate into the hole just initiated by the penetrating stylet until it emerges into the left cavity. The operation continues with the removal of the penetrating stylet out of the guide catheter, followed by the extraction of the penetrating guide (by unscrewing the screw and withdrawing the penetrating guide). This leaves only the guide catheter in place, on which a dilator is threaded to enlarge the hole. A main catheter is then put in place to ensure communication with the left heart cavity, and to allow the introduction and positioning of the detection/stimulation lead relative to the endocardial stimulation site selected by the practitioner in the left heart cavity (usually the atrium).
This technique allows a perfectly safe puncture of the septal wall. However, it also involves a large number of different components that must be manipulated (e.g., a guiding lead, a penetrating stylet, a temporary guide catheter, a dilator, a final guide catheter, a detection/stimulation lead). Moreover, if the manipulation technique follows the normal operating procedures of a trained practitioner, it remains relatively difficult and slow to execute.
It is known to employ mechanical units for cutting or penetrating tissue, such as chisel, or a traditional detection/stimulation lead that has a retractable screw lead, which is generally considered the most appropriate system for fixing the lead in the left heart cavity wall after crossing the septum. However, leaving a cutting element, even if in a retracted position, on a permanently implanted lead in the left ventricle is a concept difficult for some practitioners to accept. An alternative to using a cutting tool integrated in a permanent lead is to use a cutting tool that could be used and then removed. However, such a design would create a number of additional challenges, particularly in terms of safety of use.